Article of manufacture and method of producing same



Oct. 17, 1939. H. P. SPARKES 2,176,773'

ARTICLE OF MANUFACTURE AND METHOD OF PRODUCING SAME Filed April 26, 1937 2 Sheets-Sheet l 'il'; :59 I 220.0

F'IIR 2112 2 2- Jive-R1741. Couaucrkwrx INVENTOR hkeer 1'? Spar/(5s ATTORNEY H. P. SPARKES Oct. 17, 1939.

ARTICLE OF MANUFACTURE AND METHOD OF PRODUCING SAME 2 Sheets-Shet 2 Filed April 26, 1937 INVENTOR' liq/FRY P Spa/W055 BY NEY ATTOR Patented Oct. 17, 1939 I I UNITED STATES PATENT OFFICE ARTICLE OF MANUFAUI'URE AND METHOD OF PRODUCING SAME Harry P. Sparkcs, .West Orange, N. J. Application April 26, 1937, Serial No. 138,873 7 Claims. (Cl. 29156.4)

This invention relates to the construction and which produces a stable machine element at opmethod of producing heat-dissipating cylinders, crating temperatures. In those structures in which has as its principal object'a composite conwhich a radiating fin is welded or brazed to the struction wherein the radiating surfaces are made cylinder wall, there is only a limited joint, and

g from a material of high heat conductivity, and the compensating effect produced by the con- 6 the mechanical walls ofthe cylinder are continuous joining as herein described is not obstructed of a wear-resisting material. It is tained; in fact, exactly the reverse is accomrecognized' that considerable weight of an airplished. This is the reason why attempts to obcooled internal combustion engine cylinder is tain this result to date have been failures. Ribs it) made up of the cooling fins. If these cooling fins of a material of relatively high coefiicient of ex- 10 used on various forms of aircooled engines could pansion fused intermittently to a cylinder wall, be built rugged and yet have a higher thermal while increasing the radiation, obviously serve efficiency, the weight of the present ferrous cylinto set up strains which either break the joint or ders might be considerably reduced. This is distort the cylinder wall.

ll vitally important in aeronautics, as it would In describing my joint as fcontinuous, it is to eliminate many pounds of dead weight from the be understood that a continuous fusion of one engine of the ship. Likewise, it would be valuaelement to the other is contemplated, and over ble in the reduction of weight in stationary airan area sufllcient to produce a compensating accooled engines, or for motor vehicles, or comtion. "Continuous does not necessarily mean pressors. the enveloping of one cylinder with another, but 90 It is recognized that the dissipation of copper could mean, and is to be construed as meaning in is many times greater than steel, and it is the the application, the adjoining of two walls by purpose of this invention to construct a perfectly fusion, to such an extent as is required to effect solid cylinder fused from a cuprous material to thermal compensation without distortion of 26 act as radiating fins, and a ferrous material either member. to act as the mechanical cylinder wall. Many It is the purpose. of this invention to provide attempts have been made to accomplish this same what might be termed a heterogeneous cylinder, result, and have consisted of either the mein which it is preferred to use a cuprous material chanical joining of a copper jacket over a ferfor the radiating fins, and a ferrous material for N .rous cylinder, the welding of copper fins to the the mechanical cylinder. The thermal conduc- 80 cylinder, or by the casting of the cylinder and tivity of copper is relatively high, and the wearfins together with certain mechanical joints. ing qualities of the ferrous material is required None of these have provided a satisfactory cylinto withstand the continuous rubbing action of der, for in producing a cylinder with these qualithe piston. It is therefore preferred to use these 88 ties,itisnecessary to have aperfect thermal conmaterials, but it is understood that any other nection between e inner walls o the de combination which would produce the same effect and the radiating fins or external walls of the is-contemplated in t i ti cylmder which will dissipate the he t- The Although the cylinder is especially designed for weldmg P1700655, 9 Pmffldmg Perfect use in internal combustion engines, and in pargg m that ticular as applied to aircraft, the same principle 6 we mg produces warpmg and unbalanced obviously can be used for any problem wherein Stmms in the cylinder which results in there is desired a mechanical wearing quality on chanical failures.

Furthermore none of these Structures have the one side, and a heat-dissipating quality on the 5 provided a continuous fused joining of the two other. The principle of oining two metals to metals together. I have, in the case of a cylinheterogeneous lilgot knogm f used der, joined the two metals'continuously together m the manuFactPre of coPperweld f by the actual melting of the one into the other The Practlce 15 to provlde a Steel m to a limited. depth; and in the case of a cylinder casting which is f cor e t shape and size for head, I have joined the two metals together conmaking a cylinder. d n after Dlcklmg this 50 tinuously for a limited depth throughout the Casting. it is brought p i0 a pe ur in surface area thus effected. This is not only done cess of the melting Po Of pp and Placed in for the benefit of increased thermal efliciency of a mold, whereupon molten copper is poured the radiating surface, but also for its compensataround it to form the heat-dissipating jacket.

56 ing effect as later described in this application, This copper may be cast into shape during this operation, or may be made in a solid form suitable for machining.

Another method is, to provide a copper shell which may or may not be prefinished to its ultimate form, and to pour into the copper shell molten ferrous metal, the temperature and heat of which will be sufficient to melt into the copper, and to cause a fusion resulting in a heterogeneous mixture of the ferrous and cuprous materials, the one lapping into the other for a considerable distance. This results in a cylinder in which the external part is a metal'which has a. high heat conductivity, and an internal bore which has a lesser heat conductivity, but a higher mechanical wearing quality. The cylinder produced by this method has an advantage in that the ccefiicient of expansion of the inner or ferrous material is less than the coeflicient of expansion of the outer or cuprous material, and this permits the cylinder to expand rather uniformly and without excess strain being developed in its larger dimensions.

I have found in experimenting with a cylinder made according to the practice outlined in the application, that for internal combustion engines, this compensating feature of one metal fused to the other is very important. In the ordinary cylinder now used for automobiles and aircraft, there is a tendency of the cylinder to grow in size, due. principally to heatingand cooling. When a cylinder is heated, especially as in internal combustion engines, it is intensely heated from the interior, and there is an excessive expansion of the metal on the interior of the cylinder, and a lesser expansion of the material at the exterior.

This interior expansion is so powerful as to ac-' tually stretch the outer portion of the cylinder wall. When the cylinder cools, the exterior then being "stretched, is unable to fall back in its entirety to its original position, resulting ,in stretching the inner portion of the cylinder wall, and this repeated many times, tends to make the cylinder larger, and is known as growing. In my device, the externalmetal has the higher coefilcient of expansion, which permits it to expand more rapidly for a given rise in temperature. which in normal practice is a lower temperature than that inside of the combustion chamber. At the same time in my device, the inner wall of the cylinder has a lower coefficient of expansion and therefore expands less per degree of temperature rise,'thereby compensating for the greater heat at the interior of the cylinder. The heat permeating the cylinder wall reaches the outer jacket where the thermal conductivity and radiation is greater than the inner wall, and this.

therefore causes the outer wall to operate at a lower temperature than the inner wall. This compensated action caused by the reversal of the coefiicient of expansion and conductivity with respect to the amount of heat applied, automatically permits the cylinder to remain in a normal state without strain, and consequently not subject to the usual growing and resultant strains.

This action applies equally to the diameter of the cylinder as well as to the length of the cylinder, and it also applies to the cylinder head which likewise might be compensated for the same reasons.

This action obviously is very important in aircooled engines. It is well known that present aircraft engines have. to have their cylinders bored conical with a taper so that the explosion end of the cylinder is several thousandths smaller in diameter than the crank end of-the cylinder.

This corrects for unbalanced temperature in the head of the cylinder, and for the "growing action produced by this unbalanced temperature. After a certain number of hours of use, the cylinders have to be replaced because excessive developments in temperature have caused grow-' I lieved that these ruptures are due to metal fatigue caused by the constant stretching or growing action set up by the heat differential from the inner surface to the outer surface of the head. I have found that a temperature-compensated head overcomes this difiiculty.

The use of this compensation would eliminate the necessity of ageing the cylinder casting, as well as the head casting, before they are used, as is now the practice. The usual strains now set up in the molding of an automobile engine block, for'instance, would be largely elimina The fact that the flow of heat is from the gas generated in the cylinder into the ferrous walls and thence into the copper radiating fins, means that the expansion would be gradualand the part of the cylinder which is required-Ito expand the most is free'to, do so and at the same time has the greatest thermal conductivity. A cylinder produced by this process Zhasa perfect thermal flow and at the same time the two materials are so overlapped or fused that there are no joints to come loose or to set up, strains in the cylinder. I have found that a cylinder made in accordance with my construction and process has a great mechanical strength, and makes it possible to reduce the weight of the cylinder considerably, and furthermore, the greater coefllcient of the radiating fins on the cylinder permits of the use of smaller fins of less weight for the same radiation now obtained from a steel cylinder with steel fins. I

There are many methods by which my cylinder may be produced, and these are all contem-' plated as a part of my invention. A heterogeneous ingot with a cuprous external material and a ferrous internal material may be formed by mounting a copper shell in a foundry mold and then pouring molten steel into the center, whereupon the steel fuses the copper, and the two are completely fused together. cylinder may be machined by boring away the center of the steel coreand leaving enough steel to form the piston wall, then the copperjacket is machined into the form of radiating fins.

Another method of producing the cylinder is whereby the ingot is formed as before, and then the. copper fins are forged or pressed from the copper jacket. The bore for the piston would be machined from the center of the steel core. Obviously, the steel core could be cast hollow, so as to require the removal of less metal.

Another method might contemplate the actual forming of the fins on the .copper by a casting process before the steel is cast.

Another way to produce the cylinder is to use a steel ingot with my copper jacket fused thereto. which is heated red and-squeezed in a forging From this ingot the Figure 2 is a section showing a cylinder machined from the heterogeneous ingot shown in Figure 1.

Figure 3 is a section showing a cylinder asin Figure 1, but with the fins forged in the copper and the cylinder bored out to receive the piston.

Figure 4 is a section showing a cylinder as described in the third process, wherein the fins have been precast with the copper jacket, whereupon the steel has been poured and fused into this element.

Figure 5 is a diagram showing the thermal conductivity of steel as against copper, and explains the relative elimination of weight as a result of the higher thermal conductivity of the mate- 'rial used in the fins of the cylinder.

In describing this invention, the cylinder of an internal combustion engine seems to be the most common example andone of the largest fields of application of the principle involved, but it is not intended to limit the invention to this particular field, and for this'reason a second sheet of-drawings showing the application of the principle to radio transmitting tubes has been included.

In this application, Figure 6 shows an elevation partly in section of a radio transmitting tube in which the radiating fins are made of a material of high conductivity and the shell itself of a material of lesser conductivity but greater mechanical strength.

Figure 7 shows a section taken on the line 1-4 in Figure 6.

Figure 8 is an elevation partly in section of a radio transmitting tube in which the fins have been run in an axial direction.

Figure 9 is a section taken on the line 9-9 in Figure 8.

Figure 10 shows the application of the principle to the uprights which'support the elements within the tube.

In radio transmitting tubes, the heat to be dissipated is intense and many of the parts are constantly burned away. By use of the principle described in the invention, a satisfactory dissipation of the heat occurs and at same time the required mechanical strength for the parts is retained.

Likewise, this same principle may be applied to other parts where mechanical strength is required and insufficientpconductivity is secured through the use of the usual materials, such as the head of an internal-combustion engine. It is likewise applicable to certain heating devices, such as radiators, furnaces, or boiler parts.

It should be pointed out that in making any of these articles, it is necessary to have the copper shell of sufiicient weight to withstand the heat delivered by the iron or steel being cast against it, so as to cause only a partial fusion of the iron into the copper. Obviously, if the copper shell is too thin to withstand a partial fusion and has not sufficient body to absorb and carry away the additional heat, it would be entirely melted,

and perhaps burned away. The, copper shell' during the casting operation acts as an absorber of a sufficient amount of the heat carried in the molten steel, and this is very necessary, otherwise the steel will entirely burn away the copper and probably absorb all of the copper into itself.

It is a. purpose of this invention to include all of these possible applications wherein the process of producing a heterogeneous element with high strength on one side and increased conductivity on the other side is used.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. The method of producing a mechanical cylinder, consisting of the use of an exterior jacket with a continuous internal surface, and made from a metal of high thermal conductivity, into which is poured a lining of metal of high wear-resistance and relatively low thermal conductivity, the said metalhaving a higher melting point than the external jacket wall, and thereby causing a fusion of the internal metal into the external metal to a limited depth, and the machining of a bore through thecylinder, and the machining of radiating fins into the external jacket. 1

2. The method of producing a mechanical cylinder consisting of the use of a rigid exterior jacket with a continuous internal surface made from a metal of high thermal conductivity, into which is poured an annular lining of metal of high wear-resistance and relatively low thermal conductivity, the said metal having a higher melting point than the external jacket wall, and thereby causing a fusion of the internal metal into the external metal to a limited depth, and the machining of a bore through the cylinder.

3. The method of producing a mechanical cylinder consisting of the use of a rigid exteriorly finned jacket with a continuous internal surface and made from a metal of high thermal conductivity into which is poured an annular lining of metal of high wear-resistance and relatively low thermal conductivity, the said metal having a higher melting point than the external jacket wall, thereby causing a fusion of the internal wall metal into the external metal to a limited depth, and the machining of a bore through the cylinder.

4. The method of producing a mechanical cylinder consisting of the use of a rigid exterior jacket with a continuous internal surface and made from a metal of high thermal conductivity, into which is poured a lining of metal of high wear-resistance and relatively low thermal conductivity, the said metal having a higher melting point than the external jacket wall and thereby causing a fusion of the internal metal into the external metal to a limited depth, and the machining of a bore through the cylinder and the machining of radiating fins into the external jacket.

5. The method of producing a cylinder consisting of the casting of a rigid external jacket with a continuous inner wall froma metal of high heat conductivity and relatively low melting point, the placing of the said jacket in a mold, the pouring of an annular cylinder wall of a metal of relatively low thermal conductivity and high melting point into the said jacket, thereby fusing the one metal into the other for a limited depth, and the machining of a bore in the cylinder.

6. A bored cylinder comprising a rigid external jacket'with aycontinuous internal surface made from a metal of high thermal conductivity, into which has been poured an annular lining of from a metal of high thermal conductivity and I high eo-efllcient of expansion into which has been poured an annular lining of metal oi! high wear resistance and relatively low. thermal conductivity and low co-eflicient of expansion, the

said metal having a. higher melting point than the external jacket wall, which, when poured,

causes a fusion of the internal metal into the external metal to a limited depth.

HARRY P. SPARKES. 

